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931.
《Journal of Macromolecular Science: Physics》2013,52(3-4):369-385
The thermal behavior in dynamic conditions of polypropylene/polyamide 6 (PP/PA6) blends with a modified interphase is discussed in terms of the crystallinities of the polypropylene and polyamide components imposed by the processing step conditions and after removal of those constraints by holding the blends 5 min in the molten state in the calorimeter. As interfacial agents, two based on succinic anhydride or succinil-fluoresceine grafted atactic polypropylenes were used. The experimental program was run following the Box-Wilson experimental design methodology. Thermal scans were made using round samples (5 mm diameter and 100 μm thick) cut from compression-molded sheets with morphologies and macroscopic behavior studied previously. Changes of the amount of crystallinity of each polymer in the modified blends are contrasted with the tensile strength values of the heterogeneous materials as a whole; evidence of the different roles played by each interfacial agent acting at the interface among blend components is shown. 相似文献
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934.
Julia Vallejo Alejandro Pascual‐Álvarez Dr. Joan Cano Dr. Isabel Castro Prof. Dr. Miguel Julve Prof. Dr. Francesc Lloret Dr. J. Krzystek Prof. Dr. Giovanni De Munno Dr. Donatella Armentano Prof. Dr. Wolfgang Wernsdorfer Dr. Rafael Ruiz‐García Dr. Emilio Pardo 《Angewandte Chemie (International ed. in English)》2013,52(52):14075-14079
935.
A semiempirical method has been used to study the electronic structures of some π-bonded purely organic materials that are either known or proposed to have multiplet ground states. These materials are the precursors of organic ferromagnets. Narrow energy bands formed from the radical π-orbitals of these materials are necessary for the π-electrons to be unpaired. Favorable topological arrangements of atoms in these materials are needed to enable the spins of these electrons to align parallel, and hence yield macroscopic ferromagnetic ordering. Following ideas based on these studies, a new model for a possible organic ferromagnet is proposed and studied. 相似文献
936.
Recently, many studies have been started in search for materials which show a photoinduced phase transition (PIPT). In this work, we review two systems as typical examples of PIPT accompanied with changes in magnetic characteristics; (1) organo-metal complex [Fe(2-pic)3]Cl2 EtOH (2-pic = 2-amino-methyl-pyridine) and (2) III-V based magnetic semiconductors (In1-x , Mn x )As. In the former case, we show several nonlinear characteristics in dynamical process of photoinduced spin state transition from low-spin to high-spin states. In the latter one, photocarrier-induced ferromagnetic order has been observed by both magnetic and transport measurements. 相似文献
937.
Fouad Laoutid Marion Lorgouilloux Didier Lesueur Leila Bonnaud Philippe Dubois 《Polymer Degradation and Stability》2013
In this study, we evaluated the potential flame retardant effect of calcium-based hydrated minerals, such as hydrated lime, partially and completely hydrated dolomitic limes in polyethylene (MDPE) and ethylene vinyl acetate copolymers (EVA) and compared to that obtained with magnesium di-hydroxide (MDH). The most significant flame retardant effects, observed using the mass loss calorimeter test, indicated that Ca-based MDPE composites showed similar peak Heat Release Rate (pHRR) level to that obtained with MDH composite while the pHRR was lower for Ca-based fillers in EVA compositions. X-ray Diffraction (XRD) data, combined with thermal analysis results, indicated that the calcium di-hydroxide plays a role in the formation of an intumescent cohesive residue during the combustion. Indeed, Ca(OH)2 reacts with CO2 formed during the thermal degradation of the polymer to generate CaCO3 (calcium carbonate) that contributes to the enhancement of the mechanical resistance of the residue. 相似文献
938.
This article reviews static and dynamic models of information aggregation in the literature. It highlights the key assumptions these models make, the results they obtain and the issues that still need to be explored to further our understanding of information aggregation in financial markets. 相似文献
939.
Yu Dong Tariq Mosaval Hazim J. Haroosh Rehan Umer Hitoshi Takagi Kin‐Tak Lau 《Journal of Polymer Science.Polymer Physics》2014,52(9):618-623
This pilot study elaborates the development of novel epoxy/electrospun polylactic acid (PLA) nanofiber composites at the fiber contents of 3, 5, and 10 wt % to evaluate their mechanical and thermal properties using flexural tests and differential scanning calorimetry (DSC). The flexural moduli of composites increase remarkably by 50.8 and 24.0% for 5 and 10 wt % fiber contents, respectively, relative to that of neat epoxy. Furthermore, a similar trend is also shown for corresponding flexural strengths being enhanced by 31.6 and 4.8%. Fractured surface morphology with scanning electron microscopy (SEM) confirms a full permeation of cured epoxy matrix into nanofiber structures and existence of nondestructive fibrous networks inside large void cavities. The glass transition temperature (Tg) of composites increases up to 54–60 °C due to embedded electrospun nanofibers compared to 50 °C for that of epoxy, indicating that fibrous networks may further restrict the intermolecular mobility of matrix in thermal effects. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 618–623 相似文献
940.
Claudio De Rosa Finizia Auriemma Rocco Di Girolamo Odda Ruiz de Ballesteros 《Journal of Polymer Science.Polymer Physics》2014,52(10):677-699
The combination of the control of the concentration of stereodefects in isotactic polypropylene using metallocene catalysts and the crystallization via the mesophase is a strategy to tailor the mechanical properties. Stiff materials, flexible materials, and thermoplastic elastomers can be produced depending only on the concentration of rr stereodefects. Modulus, ductility, and strength can be modulated through the crystallization of α and γ forms or of the mesophase. Different morphologies are observed depending on the stereoregularity and conditions of crystallization. Crystals of the mesomorphic form always exhibit a nodular morphology, accounting for the similar good deformability of all quenched samples, whatever the concentration of stereodefects. The mesophase transforms by thermal treatments into the α form preserving the nodular morphology, with increase of strength while maintaining the ductility typical of the mesophase. Annealing of the mesophase permits a precise adjustment of crystallinity and size of nodular crystals offering additional options to modify the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 677–699 相似文献